In this study, the tensile and stress rupture behavior were investigated on GH4151 alloy with different grain sizes. The test samples were obtained from turbine disk with different positions. The analysis of micro-structure, grain size, and fracture morphology were carried out by several typical characteristics way, indicating that the influence of grain size on tensile and stress rupture behavior is mainly affected by the number of grain boundary, which affects tensile and stress rupture behavior of the GH4151 superalloy. The tensile strength of fine-grained specimens are higher than tensile strength of coarse-grained specimens, and so is the plasticity. At the same test condition, stress rupture life reduced from 82.5 h to 33.5 h as the grain size decreased from 22.3 μm to 11.1 μm, which decreased by 59.4%. Moreover, the elongation rate increased from 6.60 % to 25.48 % as the grain size decreased, which increased by 286%.